In a wireless local area network environment, a data frame may be transmitted via a Personal Basic service set central point/Access point (PCP/AP) (hereinafter, referred to as an AP for convenience of description) and may be directly transmitted based on a peer to peer scheme. However, in general, a transmission using an uplink and downlink to the AP may be in contention with another station (STA) in a network to acquire a channel and thus, an amount of processing may be reduced. In order to compensate for the reduction, in 802.11e, an STA may directly transmit a frame to another STA through a direct link setup (DLS) mode, not using the AP, to enhance efficiency of using a channel by at least a factor of two. However, even in the DLS mode multiple paths, attenuation, interference, and the like may deteriorate a channel status and reduce an amount of processing a wireless network and thus, may not satisfy a requested Quality of Service (QoS) for streaming multimedia.
A circumstance of a case of using a QoS such as the streaming multimedia may be remarkable in a millimeter wave such as a 60 GHz band. Even though millimeter wave communication may easily transmit several Gbps of data using about a 1.8 GHz bandwidth without a high modulation, the millimeter wave communication may have demerits of a strong straightness due to a characteristic of a high frequency and a large amount of power loss and thus, a scheme of obtaining a high antenna gain may be recommended to ease the demerits by allowing for power to be directed in a particular direction rather than all directions through use of a directional antenna. However, when a line of sight is not secured, a signal may be reflected and transferred thereby increasing a length for transferring the signal to increase an attenuation loss and adding a further loss due to the reflection. When the line of sight is blocked by a person, a penetration loss may be at least 20 dB, whereas a door or wall indoors may further increase the loss to interrupt an arrival of the signal.
Accordingly, a scheme may be used to extend a length for communication or to constantly communicate even when a direct link is blocked by using both of a direct link between a source device and a destination device and a relay link that uses a relay in addition to the DLS mode.